This poem contains one main simile and one main metaphor. Firstly, the third stanza compares the "holy dream" that Poe experiences to something that cheers him up as if it were "a lonely spirit guiding":
That holy dream- that holy dream,
While all the world were chiding,
Hath cheered me as a lovely beam
A lonely spirit guiding.
Secondly, the last stanza contains quite a powerful metaphor, as "Truth" is compared to a "day-star," or the sun, arguing that Truth is similar to the sun in the way that it is so bright and it's light penetrates from so far away:
What though that light, thro' storm and night,
So trembled from afar-
What could there be more purely bright
In Truth's day-star?
Both of these examples of figurative language help to underline Poe's message on this poem. If we remain focussed on the past, we will never be able to live in the present. To be successful in the present we need to learn to see the light that the present has for us and learn lessons from the past, taking the wisdom we have gained from those lessons on with us into the future.